What the Client says to the Supplier
Case 1 (Open Order): "I, client, promise to place every month a firm order for a given set of products / services to you, supplier, from now on and for an undertermined duration". This is discussed here
Case 2 (Subscription): "I, client, place a single firm order to you, supplier, and this order states that you must deliver every month a given set of products / services for an undetermined duration". This case is discussed here
Case 3 (Repeated Delivery): "I, client, place a single firm order to you, supplier, and this order states that you must deliver a specified quantity of items in a specified time frame at a specified frequency of delivery."
Case 4 (Recurring): "I client, place a single firm order to you, supplier. Unless specified explicitely, a copy of this order will be created every month and considered as approved by me and you".